Codeforces-1005C

https://codeforces.com/problemset/problem/1005/C

一、代码

目录

#include <bits/stdc++.h>
using namespace std;
void solve(){
    int a[122222], n, ans = 0;
    map<int, int> m;
    scanf("%d", &n);
    for (int i = 0;i < n;i ++){
        scanf("%d", &a[i]);
        m[a[i]] ++;
	}
	for (int i = 0;i < n;i ++){
        bool flag = 1;
        long long num = 1;
        for (int j = 1;j <= 31;j ++){
            int need = num - a[i];
            if ((need == a[i] and m[need] >= 2) or (need != a[i] and m[need] >= 1)){
				flag = 0;
				break;
			} 
            num *= 2;
        }
        ans += flag;

    }
    printf("%d", ans);
}
int main(){
	int T;
	T = 1;
	while(T--) solve();
	return 0;
}
// 该题方法与CSES-1640 相近